The Protein Network Surrounding the Human Telomere Repeat Binding Factors TRF1, TRF2, and POT1

Richard J Giannone,Hayes W Mcdonald,Yisong Wang,Rong-Fong Shen,Yie Liu,Gregory B Hurst,Beth A Sullivan

doi:10.1371/journal.pone.0012407

Abstract

Telomere integrity (including telomere length and capping) is critical in overall genomic stability. Telomere repeat binding factors and their associated proteins play vital roles in telomere length regulation and end protection. In this study, we explore the protein network surrounding telomere repeat binding factors, TRF1, TRF2, and POT1 using dual-tag affinity purification in combination with multidimensional protein identification technology liquid chromatography - tandem mass spectrometry (MudPIT LC-MS/MS). After control subtraction and data filtering, we found that TRF2 and POT1 co-purified all six members of the telomere protein complex, while TRF1 identified five of six components at frequencies that lend evidence towards the currently accepted telomere architecture. Many of the known TRF1 or TRF2 interacting proteins were also identified. Moreover, putative associating partners identified for each of the three core components fell into functional categories such as DNA damage repair, ubiquitination, chromosome cohesion, chromatin modification/remodeling, DNA replication, cell cycle and transcription regulation, nucleotide metabolism, RNA processing, and nuclear transport. These putative protein-protein associations may participate in different biological processes at telomeres or, intriguingly, outside telomeres.

Highlights

The terminal ends of most linear eukaryotic chromosomes contain proteinaceous-DNA structures known as telomeres [1]
The dual-tag affinity purification system was applied to all the telomere repeat binding factors, TRF1, TRF2, and POT1
In this study we explored the protein network surrounding the human telomere repeat binding factors TRF1, TRF2, and POT1

Summary

Introduction

The terminal ends of most linear eukaryotic chromosomes contain proteinaceous-DNA structures known as telomeres [1]. Telomeres are composed of double-stranded tandem repeat sequences, followed by a single-stranded, short 39-overhang which is predicted to invade the telomeric double-stranded DNA, forming a protective cap-like structure. Disruption of this ‘‘t-loop’’ configuration and subsequent exposure of the 39-overhang represent an uncapped state of telomeres [2]. Uncapped telomeres result in cell cycle arrest, cellular senescence or apoptosis and are often erroneously repaired in the form of chromosome fusions via the non-homologous end joining pathway [3,4]. This leads to fusion-breakage-fusion cycles and chromosomal fragmentation. The integrity of the telomere, especially in regards to its role in the protection of chromosomal attrition, is a vital component of overall genomic stability

Methods

Results

Conclusion